Ultrawideband ranging has been found to be valuable aiding source for indoor and GPS compromised personal inertial-based navigation (Huseth, Dewberry, & McCrosky, “Pulsed-RF Ultrawideband Ranging for the GLANSER GPS-Denied Emergency Responder Navigation System,” Proceedings of ION ITM 2011, Jan. 24-26, 2011, San Diego, Calif.) The inventors observe that these GPS/IMU/UWB navigation systems typically utilize an optimal non-linear filter, mixing multiple aiding sources to produce their final navigation solution. These filters rely on a fixed estimate of range measurement variation (“range noise”) inherent in the UWB ranging sensor. The fixed estimate is usually a conservative estimate representing an unusually large error, which consequently results in an underperforming system most of the time, particularly when the error is in fact much less than the estimate.
Thus, the inventors observe a need for improving the performance of navigation systems relying on UWB distance measurements.